A stent is an elongated device used to support an intraluminal wall. In the case of a stenosis, a stent provides an unobstructed conduit through a body lumen in the area of the stenosis. Such a stent may also have a prosthetic graft layer of fabric or covering lining the inside and/or outside thereof. Such a covered stent is commonly referred to in the art as an intraluminal prosthesis, an endoluminal or endovascular graft (EVG), or a stent-graft.
A stent-graft may be used, for example, to treat a vascular aneurysm by removing the pressure on a weakened part of an artery so as to reduce the risk of rupture. Typically, a stent is implanted in a blood vessel at the site of a stenosis or aneurysm endoluminally, i.e. by so-called “minimally invasive techniques” in which the stent, restrained in a radially compressed configuration by a sheath or catheter, is delivered by a stent delivery system or “introducer” to the site where it is required. The introducer may enter the body from an access location outside the body, such as through the patient's skin, or by a “cut down” technique in which the entry blood vessel is exposed by minor surgical means. The term “proximal” as used herein refers to portions of the stent or delivery system relatively closer to the end outside of the body, whereas the term “distal” is used to refer to portions relatively closer to the end inside the body.
When the introducer has been threaded into the body lumen to the stent deployment location, the introducer is manipulated to cause the stent to be ejected from the surrounding sheath or catheter in which it is restrained (or alternatively the surrounding sheath or catheter is retracted from the stent), whereupon the stent expands to a predetermined diameter at the deployment location, and the introducer is withdrawn. Stent expansion may be effected by spring elasticity, balloon expansion, or by the self-expansion of a thermally or stress-induced return of a memory material to a pre-conditioned expanded configuration.
Among the many applications for stent-grafts is that of deployment in lumen for repair of aneurysms, such as abdominal aortic aneurysms (AAA). One approach for isolating AAA aneurysms was described by Dr. Juan Parodi in “Endovascular Repair of Abdominal Aortic Aneurysms and Other Arterial Lesions”, J. Vasc. Surg. 21: 549-57 (April, 1995), incorporated herein by reference. This method, also known as an “aorto-uni-iliac” method, involves deploying an unbranching tubular prosthesis from the healthy aorta above the aneurysm, through the aneurysm, and into one of the two iliac arteries, so that all the blood flowing through the aorta goes into that single iliac. A portion of the blood is then transferred to the opposite portion of the vascular system (normally supplied by the opposite iliac) through a “femorofemoral bypass,” such as a prosthetic vascular graft having an end-to-side anastomosis with each of the femoral arteries. Advantageously, known femorofemoral bypass procedures involve substantially less patient trauma than conventional invasive aortic aneurysm repair. The unused iliac artery is then occluded with detachable balloons, ligation, or any other occlusion devices known in the art, such as but not limited to devices described in U.S. Pat. No. 5,499,995, incorporated herein by reference. Other methods and systems are known in the art for converting a bifurcated prosthesis to a single-lumen prosthesis for use with the above techniques when deployment of a bifurcated prosthesis is aborted after deployment of a first portion of the prosthesis, as described in U.S. Pat. No. 5,755,773 to Evans et al., also incorporated herein by reference.
Current endovascular treatment of aneurysms is sometimes contra-indicated, however, due to severe occlusive disease or tortuosity, such as in the iliac artery. Detailed measurements are typically required prior to performing the treatment. Additionally, a large inventory of size configurations may be required on hand to be able to address the variety of patients that may be encountered. The above drawbacks may preclude use of emergent techniques if the facility does not have the entire matrix of sizes available on hand at the time the procedure needs to be performed. Problems associated with a lack of having a particular size available may be exacerbated in the event of an aneurysm rupture that must be repaired immediately.
It is therefore desirable to provide a single stent-graft design that is adjustable so that one size can fit a larger percentage of patients than existing designs.